A current trend is the manufacturing of an increasing number of electronic and optoelectronic devices, such as printed circuit boards, displays and/or solar cells, on flexible substrates. Thereby, the use of cheap substrates intends to make the devices cheaper. Accordingly, there is an increasing need for and an increasing development of roll-to-roll thin film deposition apparatuses. Thus, there is a desire for platform concepts that permit low cost deposition and/or processing for different substrate materials and different stacks of thin film layers.
Further, there is an increasing demand for display elements without picture tubes. The standards for liquid crystal displays (LCD) and other display elements, in which control elements, for example thin film transistors (TFT), are used, increase. These display elements have pixels arranged in a matrix, wherein the pixels each provide an electronic device that is to be functional. Yet, also in other fields an increasing amount of elements have to be tested. This can be, for example, microelectronic and/or micromechanical elements. These elements are for example thin film transistors, connection networks of a chip, transistors, electron emitters of an emitter array, the electrodes for pixels of a display, micromechanical mirrors of an array and other elements, which distinguish themselves in particular by being present as a plurality of elements (100.000 a to several 1.000.000), whereby each element is electrically controllable.
For thin film deposition systems in the field of manufacturing electronic devices, e.g. consumer electronic devices, the testing of the electronic devices on the substrate is a task that is typically to be conducted. In order to obtain, for example, a good image quality of a display element, only a few of the several million pixels are allowed to be defective. For guaranteeing a cost efficient production it is therefore important, most notably for the display elements continuously increasing in size, to provide high-capacity in situ test methods.
Typically, flat panel displays are made of glass. These can be LCD, OLED and other flat panel displays. Yet, there are a small number of flexible displays, which are manufactured, but the process primarily is using flat glass substrate as a carrier for a flexible substrate. A more cost effective manufacturing of flexible displays is expected when the process can be done from roll to roll. For example, layers can be deposited and patterned to make a transistor array on a flexible substrate while the substrate moves from one roll to another other roll. There are also concepts to print the transistor array on the substrate. In order to beneficially reduce the costs for electronic and/or optoelectronic devices, such as displays, capacitors, solar, printed circuit boards or the like roll-to-roll processes, a testing system for electronic devices on a flexible substrate is desired.